In electronics, a switch is an electrical component that can break an electrical circuit, for example, to interrupt the current flow or divert the current from one electrical path to another. In blade- or knife-type electrical safety switches, the circuit for each phase is completed through a pivotable, electrically conductive knife or blade, which engages a corresponding contact to electrically connect the line current to the load. In some applications, the blade-type switches are mounted in an enclosure and incorporate an insulating base to carry an incoming line terminal for each phase. One such blade-type electrical switch is disclosed, for example, in U.S. Pat. No. 6,331,684, to Hamid S. Abroy et al., which is incorporated herein by reference in its entirety.
Switches can be of the fusible type or the non-fusible type. In non-fusible switches, the blade engages a contact which is directly electrically connected to the load. In fusible switches, in contrast, the blade engages a contact which is electrically connected to a fuse clip having a fuse seated thereon. The fuse is then electrically connected to the load. U.S. Pat. No. 4,302,643, to Russell Cox et al., and U.S. Pat. No. 5,777,283, to David E. Greer, both of which are incorporated herein by reference in their respective entireties, disclose fusible switch assemblies utilizing the abovementioned construction. Fusible switches are often used in switchboards to distribute power for industrial, commercial, and manufacturing applications.
In some currently designed safety switches, the voltage breaking point of the blades from the jaws takes place at one location, and the generated arc is guided through the arc housing, safely managed, and disposed. In many applications, more power must be distributed through enclosures which are the same size or smaller. For instance, as solar energy becomes more desirable, a higher voltage per pole on the safety switch will be required. This requires increasing the electrical rating of the switch to carry a higher voltage and current density while decreasing the size of the enclosure housing the electrical parts.
When the wattage across a switch is sufficiently large (e.g., 600 Vac per pole and 600 Vdc through two pole (300 Vdc/Pole)), the electron flow across switch contacts can be sufficient to ionize the air molecules between the contacts as the switch is opened or closed, forming an electric arc. The electric arc is very hot, so much so that it can erode the metal surfaces of the switch contacts. Accordingly, there is a need for a switch assembly and switching mechanism that can effectively and efficiently quench arcs generated in high voltage applications, while maintaining a sufficiently small overall footprint. The switch assembly should be economical to manufacture, and be capable of being assembled easier and faster to reduce costs. In addition, field assembly and retrofit should be simplified, and the switch should have widespread application. Another need would be to bring multiple voltage outputs into a multi-pole safety switch and be able to disconnect the power sources with a minimum number of safety switches.